Slab joint



S. KLEIN SLAB JOINT Nov. 28, 1939.

e sheets-sheetv 1 Filed May 9, 1936 :jai-'u u u 'ULI Jgl mvENmR. vJani/J //e//z .ATTORNEYS S. KLEIN SLAB JOINT Nov. 28, 1939.

Filed May 9, 1936 6 Sheets-Sheet 2 ATTORNEYS N0v.28,1939. SKLEW 'l2,181,623

SLAB JOINT Filed May 9,11936 6 Sheets-Sheet 3 MINI INVENT OR.

ATTORNEYS` Nov. 2s, 1939. s. KLEIN 2,181,623

SLAB JOINT Filed May s, 193s 6 sheets-sheet 4 97 9/ 93 95 ai 93 I ll /3/4 /5'2 u 77 l l V w l INVENTOR. Sande/Klein S. KLEIN SLAB JOINT Nov.28, 1939.

File@ May 9, 195e e sheets-'sheet 5 y INVENTOR. azfzzze/ /f/e//zTTORNEYS NOV. 28, 1939. KLEIN c 2,181,623

SLAB J0 INT Filed May 9, 1936 6 Sheets-Sheet 6 INVENTOR. .5a/7706! /2/6/'1'2 im, @W

ATTORNEYS Patented Nov. 28, 1939 SLAB JOINT Samuel Klein, Chicago, Ill.,assignorrto National Road Joint Manufacturing Company, Chicago, Ill., acorporation of Illinois Application May 9, 1936, Serial No. 18,845

22 Claims.

The present invention relates to slab joints, which are more commonlyknown as expansion and contraction joints. Such joints are providedbetween slabs of concrete and the like'in the building of concreteroads, floors, runways, artificial lakes or'pools, and numerous otherstructures made Wholly or partly of concrete or like material upon whichdestructive effects are produced by changes of temperature and weatherconditions.4

An object of the invention is to provide an improved slab jointstructure which will effectively allow for many successive'expansionsand contractions of monolithic slabs, without 'destruction of or injuryto the joint, and which can not be impacted with foreign objects orsubstances to the extent of destroying the exibility necessary for freeexpansion and contraction of adjacent slabs.

Another object of the invention is to provide an improved slab jointwhich effectively precludes entry of water or other substance betweenand beneath adjacent slabs, where destructive action ordinarily has itsinception.

A further object of the invention is to provide a joint form which maybe factory assembled at low cost, and s-hipped in the assembledcondition to the job upon which it is to be used.

A still further object iscto provide a joint form which may be erectedin sections, and eiectively spliced to furnish a continuous structurethat will not permit leakage of water or entry of foreign objectsbetween the slabs.

Another object is to provide a novel joint form structure which includesdowel pins or load transfer means, and simple means for positioning andmaintaining them in parallelism with a given line or axis.

Another object is to providein a device of the character stated,effective and durable means forconnecting and strengthening adjacentslabs in the region of the joint, to eiectually resist forces which tendto crack, break, and relatively displace the slabs.

Another object of the invention is to provide a new and impro-ved typeof flexible seal channel for slab joint structures, and a novel methodof fabricating said channel.

The foregoing and other objects are attained by the means describedherein and disclosed in` the accompanying drawings, in which:

Fig. 1 is a fragmental perspective` view of a. long dowel pin assemblyfor eiecting a slab joint in accordance with the invention.

Fig. 2 is a top plan View of an assembly similar to Fig. 1, but showingone of greater length.

Fig. 3 is an enlarged cross-sectional View taken on line 3-3 of Fig. 2,and showing, in addition, a securing stake driven into the sub-grade tohold the assembly in position.

(Ci. sul-1s) Fig. 4 is a fragmental side elevation of a joint formembodying the invention.

Fig. 5 is a top plan view of a short length' .of

seal channel which forms part ofthe joint form.

Fig.'6 is a fragmental plan vie of a joint form spliced to furnish acontinuous leak-proof form.

Fig. 7 is a' diagrammatical viewl showing a joint form end, and meansassociated with the form providing a slab strengthening structure andcooperative load transfer means, the latter com- Fig. 13 is an enlargedcross-sectional view of the Fig. 12 device, taken on line lil- I3 ofFig. 12. Fig. 14 is a cross-sectional view of a Vshort .dowel pin loadtransfer means, as used in connection -with filler joints of materialsother than metal.

Fig.- 15 is a fragmental perspective view of a removable plate whichforms part-of the Fig. 14 .construction.

Fig. 16 is a detail perspective view of a premolded ller element thatmay-be applied to the' joint Iform after formation of adjacent slabs.

Fig. 17 is a fragmental side elevational view of a joint form of modiedconstruction.

Fig. 18 is a cross-sectional View taken on line i8|8 of Fig. 17. Figs.19, 20, 21, and 22 are views illustrating a series of steps andapparatus employed in a process for the manufacture of seal channelswhich form part of the present invention.

For purposes of convenience and clarity of un'- derstanding only, andwithout limitation of the )present invention t0 any particular use, theinvention will be described as applied to a concrete roadway comprisingadjacent spaced slabs poured during construction of the roadway. ATheuse of roadways by heavy trucks and other vehicles operating at highspeeds has, in the past several years, presented a number of truestructural concrete problems. As is well known, concrete presentsproblems in various forces, namely, compression, diagonal shear, trueshear, tension, and diagonal tension, the vproblem being magnified andrendered increasedly complex d ue to the nature of the present daytrafila. The usageof of compressible and shifting subgrade presents astructural cantilever problem, involving in addition to simple verticalshear, the far more critical element of bending, with resultant directtensions, compressions, and what is most serious in concrete, diagonaltension. One need only examine concrete highways of the past few years,to reach the conclusion thatI the deleterious effects of the forces towhich the roadway is subjected, have not been overcome. The effects ofthe forces above referred naturally have been manifest at the expansionjoint, where premature checking and cracking are most likely to occur.Even the use of load transfer elements across the joints, and highstrength concrete mixtures, have not solved the problems mentioned,vpartly because of faulty design and placement of the load transfermeans and partly because of the lack of appreciation of the magnitudeand directions of the forces acting to crack and break the slabs thatcomprise the roadway. A niostcommon cause of premature breakage andcracking of the concrete along the joint, was attributable to slabconnecting means of extensive4 area, imbedded in the adjacent edges ofthe slabs in such a manner as to. render impossible the proper andsuiilcient bonding of the mass above and below the imbedded slabconnecting means. Another fault of prior joint constructions resided inthe failure to vexclude water and other foreign substances, whichinvariably promoted upheaval by freezing beneath and between the slabsor, in the case of the admission of dense particles, caused completeclosure of theLjoint and precluded normal'expansion of the slabs,resulting in heaving, crumbling or cracking of the concrete at locationsnear the joints. The elimination of all these faults has been taken intoconsideration in designing the joint structure of the present invention,so that the region of the slab joints will withstand the injuriouseffects of fast and heavy traflic, temperature changes, and waterconditions, for a period of time corresponding to the life of the restof the pavement.

With reference to the drawings, it shouldbe noted that the character Gindicates the subgradeand that the character L in all the illustrations,indicates the level of poured concrete which constitutes the slabs S.

Figs. 1 to 4 inclusive, illustratev a slab joint structure of the longdowel pin variety, including various improvements over the long dowelpin structures heretofore employed in the construction ofconcreteroadways. The characters 20 and 2| indicate constructionelementsknown as road rails, said rails being employed to establish ordefine the lateral limits of a slab to be poured. The road railsgenerally are positioned accurately to not only define the width oftheslab, but also to establish thethickness oi' the pavement. Underordinary circumstances, the road rails are parallel to each other and tothe axis of the. roadway.

Within the limits er the raus, there is peei-` tioned a joint form,indicated generally by the character 22, whereby adjacent slabs areinitially spaced apart a proper distance toallow for natural expansionand contraction o f the slabs.` 'I'he dowels or shear pins 23 areadapted to extend 'site ends of the dowels or shear pins 23.

it insures a free straight-line expansion and contraction of adjacentslabs, without undue strain and wear between the dowel pins and theconcrete in which they move when the slabs are set and begin to expandand contract under varying temperatures and water conditions.

The dowel frame referred to may comprise a pair of transverse rigidmembers 25, which may be in the form of angle irons if desired, saidmembers being preferably of a length approximating'the distance betweenthe road rails 20 and 2|. At measured distances from the ends of themembers 25, are fixed a series of dowel sockets 2 6, the spacing of thesockets being such that the sockets of each ofthe transverse elements 25provide pairs of sockets for reception of the oppo- When the oppositeends of the dowelstor shear pins automatically assumepositions inparallelism with the roadway rails, and since the transverse ele-vpositions other than positions of parallelism to ils.

one another and to thel road r Each socket supporting member 25 isprovided' with suitable shoes or standards 21 which support the socketsupports at a proper elevation above the subgrade, The shoes may beriveted orv otherwise securely fastened to the members 25, as indicatedat 28 of Fig. .3. To render the shoes adjustable to the subgrade, and tosimplify shipping or crating problems, the rivets 28 may be suiicientlyloose to provide'lfor rotation'of the fshoes to substantial parallelismwith the vertical plane of the socket support member 25. To provide forinitial expansion of the slabs, certain ones of the dowel sockets may beprovided' with destructible space thimbles 29 which are so positionedwithin/the sockets as to assure expansion spaces'30 for the dowels.Thus, by refere ence to Fig. 3; it will be understood that movement ofthe slabs S toward one another will result in advancing the dowelsockets toward each other, causing the dowelor shear pin 23 to crush thethimble 29 in the rear end of the socket, thereby preventing cramping orendwise compression of the dowels by the irresistible force of expansionof the slabs. The sockets may be flared at their open ends, as indicatedat ,31, for easy reception of the dowel ends, and the slots 32 of thesockets, which afford a resilient or yielding connection between thesockets and the dowel ends, are closed by the space thimbles 29 toprevent entry of grout into' the space 30 reserved for the dowel endsupon expansion of the slabs toward one another. The entire dowelassembly may be held in position by means of suitable stakes 33, or theassembly may be suitably wired together to prevent relative shifting ofthe parts.

`As will be evident, expansion of the adjacent slabs toward one anothermust not meet with resistance at the jointform member 22. The joint formis accordingly made in the manner disclosed in either of Figs. 3 and 8.The construction illustrated in Fig. 3 will first be described.

The side walls 34 and l5 of the form may be constructed of pressed sheetmetal secured together in such a manner as to provide a communicatingJoint chamber 3l and seal` channel material, is extracted from elements,and also chamber 31. The seal channel chamber is preferably, though notnecessarily, provided with opposed locking beads 38 and 39, which holdin position a continuous seal channel 4I) that extends inwardly past thebeads and into the chamber 31. Extended outwardly of the channel, at thetop thereof, are the flanges 4I and 42 and the anchor arms 43, theflanges and anchor arms being imbedded in the concrete slabs. Suitabledepressions 44'may be provided in the anchor arms to provide-a lockinadditionA to the lock provided by each anchor. Before the slabs arepoured, a temporary slab separating member 45 isinserted into the sealchannel 40, and as disclosed iny Fig. 1, said separating membercompletely closes the seal chamber across the top and along the endsthereof. After pouring and setting of the concrete slabs, the slabseparating member 45, which is preferably of metal or other nonporousstrong replaced by apremolded bituminous mastic ller element 46 (Fig. 4)having substantially the same shape as the temporary slab separatingmember 45. It is to be understood, of course, that the mastic or plasticsubstance kept in a' fluidl or semi-fluid state on the job, may bepoured into the channel 40 and the space between the slabs as asubstitute for the premolded mastic element 46, if desired. Thepremolded element, however, affords a convenient manufactured iillermeans for expansion joints of the character described,

and may be used 1n lieu of the metal separating member 45 aforesaid. Thecontinuous seal chanf nel as disclosed in Figs. 1, 2, 3, and 5,preferably is fabricated of copper or other suitable material which willwithstand the destructive action of the the repeated distortion to whichit is bound to be subjected by the expansion and contraction of theconcrete slabs. Further details concerning the flexible seal channelwill be treated hereinafter.

The interior of the joint form is required to be waterproof, and theform must be so constructed as to crush readily when the slabs S expandand move toward one another. For this reason, side wall 34 may beprovided with a spacer, which may be in the form of a button 45, thecrown of which is adapted to abut another button carried by the spacedwall. The button 41 is rendered deformable by providing a third button48 over it so as to furnish an air space 45 into which the concrete cannot enter when poured against the side wall 35 of the joint form.. Inorder to provide the air space 4S the inner face of the side 35 isprovided with an assembly plate 50 which may be spot welded or otherwisefixed to the wall 35, and clinched at its lower end 5I within anenclosing double flange 52 that forms part of the base of the joint form35. The ange 52 may be spot welded to the lower edge 5| of theconstruction plate 50, to provide a rigid structure. The free end 53 ofange 52 extends across the joint chamber 3B at the base of the form, andis slidingly received, between a double base flange 54 of the oppositewall 34, thereby to provide a sliding fit of end 53 in base part 54 andallowing for free expansion of the slabs toward one another in theregion of the base of the joint. At approximately the location 53, aseries of weak spot welds may be resorted to for temporarily binding theelement 53 to element 54, thereby keeping the structure assembled duringshipment and placement thereof on the job. It will be noted that thesubstantially horizontal free end 53 of the joint wall 35 provides aseal forexcludthe channel 4B and the ing from the joint chamber 36 anygrout or foreign material from the sub-grade. It is of `course evidentthat water seepage past the seal channel 40 and into the space betweenthe joint form walls, is impossible due to the fact that the seal anges4I and 42 are imbeddedin the slabs to provide a continuous seal from thebottom of each slab, a, t the sides thereof, upwardly along the sidesand across the tops of the slabs.

It is important to observe that the seal flangesA 4I and 42 are notextended into the slab ends for any considerable distance, and theanchor arms are likewise short and considerably spaced apart so as topermit extensive and suicient bonding of the sab material in the space55 between the arms. It may here be stated that many expansion jointfailures are properly attributable to the provision of extensive sealflanges and anchor arms which, in effect, separated the relatively thinconcrete portion above the seal flanges, from` the concrete below theflanges. In the present invention, adequate space has been provided'between the anchor arms t0 permit substantially uninterrupted bondingof vthe concrete above and below the parts of the seal channel that areanchored in the slabs, so A that there is no appreciable dividingstructure between the concrete above the seal channel anchorage,lfromthat below the anchorage. The seal flanges accordingly are made asnarrow as possible for preventing water seepage into the interior of thejoint form, and the anchorages themselves are of minimum area andvextent to avoid separation of each slab into disconnected or unbondedparts. I have found that satisfactory results are obtained bypositioning the flanges 4| and 42 at a distance below the upper face Lof the slab, approximating three times the width of the flanges. For.example, each of the flanges 4I and 52 is of a one-half inch width,intermediate the anchor arms 43, and are disposed one and one-halfinches below the face L of the concrete slab. 'I'he referred to width ofthe flanges is indicated at W of Fig. 5. The anchor arms 43 are spacedat such a distance from one another, as to have no effect upon theindicated 3-to-1 relationship stated, and they function only asanchoring means for the outermost or free edges of the flanges 4l and42. The depressions or corrugations t4 are provided in the anchor armsto strengthen the arms and furnish additional anchorage in the concrete.

The openings 24 of the form walls 34 and 35, are flanged inwardly asdisclosed in Fig. 3, so as to support a corrugated or collapsibleferrule 56 which forms'a passageway for the dowel and provides a closureor seal between the passageway and the hollow interior of the form. Itwill be noted that opposite ends of the ferrule fit about the inwardlyturned flanges of the dowel openings, and are thereby maintained inplace after assembly of the joint form. The ferrules may be of anysuitable construction, those illustrated being in the form of cylinderscorrugated at several locations between their ends, so that the ferrulesmay be deformed or collapsed in the manner of accordion pleated devicesor bellows structures. It will be noted that the ferrules preclude entryof grout into the hollow interior of the joint form, even though thedowels may not fit tightly therein. 'v space for collapse of theferrules, the metal surrounding the openings 25 preferably is bulgedoutwardly as at 51. Other bulges 58 in the side walls of the form, atthe sides of the seal chanends of each joint form, so that entry ofgrout or other foreign substance is effectively preinclude collapsibleferrules.

separate heavy plate 1I, one end.12

,snap action holding means which sleeves 16 effectively seal saidopenings. channel member III nel 40, permit a maximum movementof theslabs toward'one another without injury to the seal channel. It is to beunderstood that the bulges 59 indicates a block or plug of rubber orothersealing material which closes any openings that might occur wherethe seal channel 48 and its component parts meet the base of the jointform. A plug or seal such as 519 is provided at opposite vented.

In instances where it is necessary or desirable to tionship, 60 isemployed. 'I'he splicing element may be constructed in various ways,that indicated in Fig. 6 being a plate of rubber, mastic or the like,having substantially vertical edges BI and a horizontal upper edge 62,the meeting points of said edges being curved as at 63 complementarilyto the curve o f the seal channel 40 where the channel turns fromhorizontal to vertical disposition. 'I'he splice member 60 is of suchthickness as to fit snugly within the vertical run of the seal channel,and partly about the vcurved portion thereof at 63, so as to dispose thesplice joints within 'the confines of the joint forms,'rather thanexteriorly thereof. The height f the splicing member 80 preferably issuch that a continuous length of preniolded mastic ller may rest uponthe upper edge 62 while extending along the horizontal runs of thechannel of the spliced joint forms. Joint form splicing means may beconstructed also of metalsand such will hereafter be described inconnection with Fig. -12 of the drawings.

Fig. 7 is an end view showing diagrammatically a joint form having theside walls 6I and 65 and a base B6 adapted to rest upon the subgrade,the upper portion of the'form carrying" a mastic ller B1 insubstantially the same manner as the device of Fig. 3 carries the slabseparating member 45. 'I'he form of Fig. '7 is provided with the spacerbuttons for the' purpose previously described and the opposed side wallsof the form have openings 88 and 69 for reception of a short shear pinor dowel 1U, all of which is most clearly shown in Fig. 8. Inthemodified structureof Figs. 7 and 8, the base of the form includes a ofwhich is clamped within the clinch structure 13 formed at the lower endof the assembly plate 148. The includes the locking beads 14 aresubstantially the same as, disclosed in Fig. 3. It will be noted,however, that the joint form of Fig. 8 may or may not .The metalsurrounding the openings 68 and 69 isnot pressed outwardly in the mannertion. The sides of lthe form are flat in the region of the dowel or pinopenings and the large flanges 15 of the pair of shear pin bearings orThe place two joint forms 22 in end to end relaas disclosed in Fig. 6, asplice element of the Fig. 3 construcl ymay be extended along the ,fbottom ot the form members and il. In auch y.

' construction the form members 6I and 85 are V preferably curved at thelower outer edges thereof as well as at the upper outer edges thereof.This form of the invention is shown in Figs. 17 and 18. It is to beunderstood that the opposite ends of the member 40 will overlap or bejoined in any suitable manner to provide a continuous member.

'I'he shear pin bearings or sleeves are adapted to be imbedded in theconcrete slabs at op'posite sides of the joint, so as to structurallyreinforce the adjacent ends of the slabs. One end of the shear pin 10 isfitted tightly into the bore 11 of one of the bearings or sleeves, forexample, the one at the left of Fig. 8, while the bearing or sleeve atthe right very snugly but slidably receives the opposite end of thedowell or shear pin.k

A convenient mode of `securing the snug or tight t of the dowel ends inthe sleeves or bearings, without danger of absolute fixation, is toroughen or knurl the dowels as at 210 along a portion of their length,and preferably at a distance from the dowel ends so that the dowel endsmay be started into the sleeves with ease, and thereafter pressed orforced in place. For a better illustration of the knurled or roughenedportion, Fig. 14 may be referred to. That end of the shear pin or dowelwhich is adapted to slide within a bearing or sleeve, which end may bethat end indicated by the character 18, may be protected from entry ofgrout in any suitable manner such as by means of a closure plate 19 atthe outer end of the bearing or sleeve or by closing the end at 19 inthe forming of the sleeve. This provides an air pocket 180 at one end ofdowel 10.

When the Fig. 8 construction is assembled at the factory, the dowel orshear pin andthe pin bearings or sleeves are applied, so that the entireassembly may be placed on the subgrade as shipped from the factory. Theparts cannot be disconnected because of the tightness of the fit between`the dowels and the s'leeves. The assembly may be shipped from thefactory with the l mastic filler 61 applied, ora slab separating membersuch as 45 of Fig. 3 may be substituted therefor, said separating memberto be removed and replaced with a mastic filler after pouring andsetting of the slabs. 'Ihe Fig. 8 assembly may be staked to thesubgrade, or otherwise rigidly supported during the pouring of theslabs. The bottom closure plate 1| may be of rust-proof material, sothat it will remain in position for excluding entry of solid materialsinto the hollow interior of the formfor to the space between the slabs,long after the form has rusted away. The

continuous seal channel which holds the filler 61v may be identical withthe channel of Figs. 1 to 5 inclusive, and is adapted to extendhorizontally across the form and vertically along the vertical side-edges thereof in substantially the manner disclosed in- Fig. 4. Theshear pin` bearings o r sleeves 16 are provided withsuitable ribs andbearing faces 80 and 8|, as well as with flanges 82, for effectivelykeying them in the material of the slabs. referred to as wings or wingbearings having upper and lower faces substantially horizontal in theslabs, to afford substantial resistance to vertical wearing of thesleeves 1l inthe slabs. It will be noted that the dowel of the forms ofthe present device, is disposed in a plane which substantially evenlydivides the thickness of the slabs. It. should be noted also that thedowels support Qta weight of the joint fonn, rather .than the formluprtmg the weight of 'I'he flanges 8| may more properly bev or shearpin in ,all

the dowels, in Figs; 1,-3, 4,and 14. In instances where the structure ofFigs. '1, 8 and 11 are provided with dowel bearings of the typedisclosed in Figs. 9 and 10, the weight of the joint form is likewisesupported by the dowels", the object vof this being to facilitatesetting of the joint form at right angles to the subgrade, and to insurea substantial setting for the joint form structure. It will be notedthat the bearings or sleeves 83 of Figs. 9 and 10 are similar to thebearing or sleeve shown in Fi'gs. '7 and 8, except for the addition of ashoe 84 which rests on the subgrade, and which may be secured thereto bymeans of one or more stakes 85. The leg 86 which connects 'the shoeportion to the bearing or sleeve portion may be of any desirable shape,a straight leg being shown in Fig. 9and a curved leg being shown-in Fig.10. The figures just mentionedv naturally suggest legs of angular orother configuration.

At this point'in the description, it is appropriate to consider variouscharacteristics of the dowels and the dowel sleeves or bearingsmentioned in the precedingparagraph. In computing and testing for adetermination of a proper length and diameter for the dowels, it wasfound that extreme length was unnecessary, and that a small diameter ofdowel would easily withstand the shear forces that occur betweenadjacent slabs. The use of a small diameter dowel, however, provided aninsumcient bearing in the concrete of the slab, so that loads on theupper face of the slab caused the dowel to shear the concrete in whichit was imbedded. To overcome this destructive shearing action, it wasdetermined that suiiicient bearing could be furnished to distribute theload, by making the dowels of a larger diameter than was necessary totake care ofthe vertical shear between slabs, but dowels of such a largediameter were found to be an expensive expedient. Further efforts tosolve the problem eventuated in the provision of the disclosedconstruction comprising dowels of small diameter suitable to take careof the shear between slabs, associated with the larger diameter dowelbearings or sleeves to be embedded in the slabs for increasing thebearing area and thereby distributing the load over substantial bearingAareas in the slabs. The actual diameter of the bearing or sleeve washeld to a minimum by providing the horizontal sturdy wings or bearingeX- tensions indicated at 8|. The enlarged areas of the dowel bearingsor sleeves not only provide for effective load distribution, but theyprevent breaking down of the bond between the concrete and the bearingor sleeve elements. Instead of the dowels sliding in the concrete, theyslide in the bearings or sleeves, upon expansion and contraction of theslabs. f

Attention is now directed to the general combination disclosed in Fig.'1, which exemplifies a complete set up for obviating the destructiveef,- fectsof the various forces referred to in the introduction whichfollows the description of the 'drawing figures. Besides the dowel orshear pin structure disclosed in detail in Fig. 8, the combinationincludea pair of wire mesh reinforcement elements 81 ,each of which isin the shape of a long invert-ed channel having supporting legs 98 and89, and an intermediate horizontal portion 99.

The portion 99 is adapted to be disposed comparatively close to theupper surface of the slab, while the supporting leg |39 rests close-to,an adjacent wall. of the` joint form. This type vof reinforcement isadapted to tie the concrete mass together in a plane well above themiddle of the slab, so as to overcome the torsional, bending, andcantilever forces which would occur in the upper region of the slabs inthe event of undermining of the subthe mesh reinforcement in the lowerportion of the slab. It should be understood, however, that meshreinforcement in the lower portion of the slabs may be provided for, ifdesired, bymaking the member 81 in the shape of a tube having four ormore sides instead of the three sides indicated by the characters 88, 89and99. The bearing or sleeve structures disclosed in Figs. 9 and 10 mayreadily find application to the general combination of`Fig. 7, as willbe understood. It should be noted also that reinforcing mesh meanshaving substantially the characteristics of those indicated at 81, areapplicable to joint form assemblies as shown in Fig. 1 as well as inother than those specifically disclosed in the present description andillustrations.

Fig. 11 discloses the joint form of Fig. 7, in side elevation, withouta'showing of the mesh rein-l forcements 81. It will be noted that Fig.11 includes a pair f premolded mastic end pieces 9| and 92, each ofwhich has a horizontal leg 93- and a vertical leg 94. The freevend 95 ofeach horizontal leg is adapted to abut the opposite ends of anintermediate length 96 of premolded mastic supported-within the sealchannel 49 of the joint form. r The separation of the mastic filler intoend pieces and intermediate sections has several advantages, some ofwhich are a reduction in cost of manufacture, ease in handling andshipping, and the like. A further advantage is that the end mastic piece93, for example, may be removed to advantage when it is necessary ordesirable to Splice two joint forms in'end to end relationship. Toeffect the splice just mentioned, it is necessary only to remove the endsection of premolded mastic filler piece 93, and to replace it with astraight horizontal section 91 of premolded mastic filler carried by thesplicing member 98.` The latter may be of the character disclosed inFig. 6, or it may be of metallic construction as disclosed in Figs. 12and 13. The side walls 99 and |90 of the'splice member are spaced aparta proper distance to enable them to enter and snugly t within thevertical run |9| of the seal channel 49 of Fig. 11. It will be notedthat the splice member itself has a base portion |92 and a channelsupporting portion |93 similar to the corresponding -parts of the jointform. The length of the Abase portion |92, however, is somewhatdiminished so` as to substantially abut the base portion |93 when theside walls of the splice member are inserted into the seal channelsection |9I. Like the joint form itself, the splice member may beprovided with a seal channel member .|94 corresponding vto the sealchannel member of the joint form. Thus, a pair of joint forms connectedby'means of a splice member of the character disclosed in Fig. ll2, willbecome a continuous or composite joint form of a desired length. It ispreferable, though not necessary,rthat the Splice member 98 u ends ofthe pin are received in the pin bearings l the lower edge thereof.

be provided with the collapsible button arrangement |05, whichcorresponds to that of Figs. 1, 7 and 8. It is to be understood,further, that the side walls of the joint, as well as those of thesplice members, may be provided with spacing means of a type other thanthe button type.

In Fig. 14 is represented an expansion Joint including load transfermeans of novel construction, without the inclusion of metallic jointforms. In this modification, |06 indicates a long sheet of preformedmastic material, rubber, or the like, of a height approximating thethickness of the slabs S, supported `,upona short dowel pin |01. 'I'he|08 and |09 as explained in connection with Figs. 'I and 8. The-pinbearings may be provided with either of the leg and foot membersdisclosed in Figs. 9 and 10, to support the mastic sheet in asubstantially vertical position between the enlarged faces of theflanges and ||2. To impart the necessary rigidity to the mastic sheetbefore the concrete is poured, a metal platel I3 of a substantialnature, is placed beside the mastic sheet and supported in asubstantially vertical position between the flanges ||2 and ||4 of thebearing or sleeve |09. To provide for removal of the metallic plate I3after the concrete slabs are set, a slot is provided therein extendingfrom approximately the middle of the metallic sheet to countersunk as atH6, to provide a fin ||1 that fits quite accurately between the flanges2 and 4 to maintain the removable plate substantially at right angles tothe axis of the load transfer dowel or pin. Upon removal of the metallicplate i3, the mastic filler remains in position to permit expansion andcontraction of the slabs S, While the dowel and dowel bearing elementsperform'to maintain thev alignment of the slabs. The space remainingafter removal of the plate N3 may be filled with fluid or semi-fluidmastic, if desired.

In Fig. 16 is disclosed an end portion of a premolded hollow joint llershaped to tthe channel seal of a. joint form, said filler beingconstructed of rubber or composition material. When constructed ofrubber or like' substances, the filler not only performs to precludeentry of water intorthe slab joint, but lit also tends to expel from thejoint any foreign particles capable of compacting and solidifying withinthe* joint. The channels or air spaces may be varied to meet therequirements of the construction work in which the filler or closure isto be employed. The vertiealleg |20 is adapted to extend to the baise ofthe joint form, as disclosed in Figs. 1, 4, and 11.

AReference is now made to the modification shown-'in Figs. 1'1" and 18iwherein the seal channel 40 extends entirelyv around the joint,

form structure rather than along only' the top and sides thereof Fig.11, for example. ,When the seal flanges 4| and 42 and their anchor arms43 are embeddedin adjacent slabs of concrete, there naturally results acompletely'enclosed airspace which is definedv by the seal channel.'I'his air space is permanent, due to the fact that theseal channel ishighly resistant to corrosion and the destructive effects of theelements, it being of copper or similarly 4permanent metal. Also, thesealI y channel .expands and contracts laterally Ylike a The walls ofthe slot are as explained in `connection with form therein to fill thespace and interfere with free expansion and contraction of the slabs.

The characters |21 indicate sheets of mastic or bituminous ller, or ofrubber, supported within the seal channel as heretofore explained. 'I'heseal channel may be provided with the snapaction locking beads |28 tomaintain the channel in position relative to the opposed form walls |20and |30, all as explained in the description of other forms of thedevice. In' all forms of the invention, the form walls which support theseal channels are made of inexpensive sheet metal, such as 'ironsheeting or low grade steel. The form walls developed from -thismaterial are intended to render rather temporary service,

namely providing a space between adjacent slabs of concrete andpositioning the non-corrosive seal channel 40, the dowels, their bearingor sleeves, and the base plates such as 1|, until such parts are firmlyembedded in or anchored relative to the slabs of concrete. Thereafter,the form is expected to rust away or, corrode, leaving intact the sealchannel and the load transfer elements.

The seal channel of the Fig. 17 and Fig. 18 device may be made 'in oneor more sections welded, brazed or otherwise suitably joined as at theoverlap |3|.`V The exact manner of making the channel continuous is, ofcourse, immat/arial, except that theA method of manufacturing orfabricating it is believed to be novel, and the method will hereinafterbe disclosed.

The form dis'closed in Figs. 17 and 18 may be supportsherein disclosed.Attention may be directed to Fig. 18 for an excellent disclosure of theknurled or roughened portion 210 of the dowel or shear pin 10.' Theseveral Icharacters |32 of Figs.'1'7 and 18 indicate spacer buttons suchas were described in connection -with Figs. 3, 8 and 13, and at |33 isshown a corrugated cylinder or ferrule corresponding to the element 56of Figs. 3 and'8. In the Fig. 18 modification, the use of thecorrugatedcylinder is, not ordinarily required, though it is permissible.

It should be noted that Figs. 17 and 18 disclose an importantmodification of the Fig. 10 dowel bearing or sleeve member, whichconsists in the addition of one or more vertical extensions |34 havingfree linear 4edges |35 adapted'to reach and abut the bulges |30 or othersubstantial projecprecluding rotation of the bearings or sleeves may,./

ofcourse, be of 4one design or another, but in the preferred form, suchrotation-precluding means should not penetrate the form wall andthereby'` allow for possible entry of grout. By providingcooperativemeans as stated, for precluding rotation of the dowelbearings or supports relative to the form walls, a rigid and sturdyassembly is made possible by the mere forcing of the right- 1 handsleeve 83 onto the corresponding end of the dowel, until the knurledportion 210 snugly enters the sleeve. 'Ihe abutments at |35+|36thereupon will be engaged, to prevent rotating of the sleeves, while at'the same time the ange or plate portion 31 of each sleeve will flatlyabut the form and prevent grout from entering be-l tween the form wallsthrough the dowel aperture,

in the absence o f a cylinder such as |33. As will be readilyunderstood, a single abutment such as |35 on each dowelbearing supportmember,

shape that is'merely punched and shaped in an ordinary manner. Thesealing channel referred to throughout this description is indicatedgenerally by the character ,40, it being unnecessary to again explainthe function and nature of 'the sealing flanges and anchor portionsthereof. In the manufacture of the sealing channel (Figs. 19, 20, 21 and22), a strip |40 of metal of proper width and length to t a. joint form,is fed to a press and cutting die mechanism for the purpose of formingthe extending arms 43 thereof as illustratedinrigiamsmuchofthetreatmentf of a strip may be formed by ordinary means, whichmay be either rolling dies or reciprocating press elements, and ifdepressions such as 44 ofl Fig. 5 are to be made in the extending arms,such can be accomplished in the same operation. As the next step of theprocess, the strip of Fig.A 19 is subjected to a simple pressing.operation which imparts thereto the formation disclosed by Fig. 20,wherein the characters |4| and |42 indicate the locking beads cf theseal channel. The pressing operation last mentionedis applied to only anintermediate portion of the strip, leaving a foot or two of the ends inthe formation disclosed by Fig. 19. This intermediate portion thereuponis subjected to pressing dies such as |43 and |44 of Fig. 21, wherebythe strip, excepting the ends thereof, is given its finalcross-sectional configuration as seen in Fig. 3. The ends of the strip,it should be noted, are still in the Fig. 19 condition. These ends arethen subjected to a special treatment whereby they are pressed toform'the vertical channels and curved to fit a joint form end, all asdisclosed in Figs. 4,- 6 and 11. 'I'he curving of the strip end involvesnot only a press operation, but also a simultaneous stretching'operation upon the end undergoing pressing. To accomplish this, thestrip end is placed lengthwise between a convex die |45 and a concavedie |46, said dies having complementary tongue and groove elements |41and |48 for pressing the channel groove into the strip end. The upperdie has one or more pressure blocks or plungers |49 which engageand holdthe strip while it is being curved and channeled, the eiect of suchengagement and holdingbeing to stretch tlrev strip end longitudinallywhile it is being pressed into channel formation. For example, the stripend of Fig. 19 is rst bent transversely to lfit between the die parts|45 and |46. As the die part |46 descends, the tongue and grooveelements |41 and |48 thereof begin to channel the strip end, but atsubstantially the same time, the spring plungers or pressure blocks |49are pressing tightly against the tongue with the meterial of the stripinterposed, so'that further downward movement of die part |46 mustproceed while the blocks or plungers arrest downward feeding of thestrip towardA the apex'of the die, The further downward advancement ofdie part |46 causes the plungers to more tightly hold the material ofthe strip while the plungers pivot outwardly about their mounting pin's|50. As is evident from the disclosure of Fig. 22, the plunger works ina sleeve( |5| and said sleeve is pivoted at |50 so as to be capable o fmovement through the recess |52 in the die part. 'I'he pressure springis shown at |53. The holdingaction of the plungers or pressure blocksresults in a stretching of the metal of the'channel strip in the regionof the base thereof, and Vthe effect of the stretching is such as toprevent crinkling and crystallization of the metal which forms the baseof the channel, while the tongue and groove elements press the curvatureinto the strip. The stretching force is regulated so as to elongate thechannel strip to the extent of prventing compression of the structureofthe metal at the inlside of the bend Vor curve, so that the metal atthat location will be of substantially the same thickness as the metalof the channel alongv the straight portions thereof. By reason of thismanner of treatment, the metal of the channel is rendered quite ductileand free of initial crystallization, with the result that repeatedtransverse expansion and contraction of the channel at the curvedportion thereof is made possible without danger of early breaking orcracking.

After the stretching and bending operation just described, the channelstrip may be rolled or otherwise treated to form locking beads along thecurve, if desired. It should be understood that other methods of curvingand stretching the channel member may be capable of operating upon thechannel member after formation of the bead |25, but whatever may lbe thespecific nature o f the process or apparatus involved,-I claim as myinvention the curving and stretching of a channel member, eithersimultaneously or alternately, for the purpose of rendering the curvedchannel member capable of withstanding a much greater number of lateralexpanding and contracting forces than could be withstood by a curvedchannel member when not treated in accordance with the invention. Theuse of copper or similar metal forV the channel member is consideredpreferable, due to its ductility, its resistance to deterioration, andthe ease with which it may be worked in the formation of the channelmember. It is conceivable, of course, that various alloys having thecharacteristic mentioned, may furnish the same advantagesas'the metalmentioned, and that the curvature and stretching above explained may beproduced by the use of a roller die.

The copper sealing channel in practice, is in. `tended to flex as may berequired due to temperature changes and consequent expansion andcontraction of the slabs. By forming the curved parts of the channel 40at the ends of the forms in accordance with the method explained herein,

it is possible to`assure-numerous contractions,

expansions, extensions or other movements, before crystallizationrenders the seal ineffective. In fact, tests have shown that thesecurved parts of the seal channel will function as'long or as often as dothe intermediate portions of the channel. A seal of the characterdisclosed herein will easily function for the estimated life of a modernconcrete roadway,'namely, thirty years, before failure of or destructionofthe Seal. Tests establishing these facts have been conducted inaccredited testing laboratories. Y

The` devices shown herein are preferably assembled at a factory and areshipped to the job as complete units, one each of which is positioned ateach place at which an expansion joint the -recesses along is desired.By so 'assembling and positioning the expansion joints 'as-separate.units, it is possible to obviate the errorsthat commonly occur asaresult of carelessness and `incompetence of unskilled labor that is nowvrelied on/to position expansion forms heretofore used' and built up onthe job.

Preferably the beads Hl and |42 do not extend around the corners orcurves ofthe seal channel 40 because of slight manufacturing variancesvside walls each having upper and lower edges' and an end, said endsbeing curved where they meet the-upper edges of the walls, and acontinuous integral ductile sheet metal seal channel depressed betweenthe sidewalls, following the curve and extending along the upper edges`and ending adjacent to the lower edges at the ends of the walls.

2. A slab joint form comprisingfa pair of spaced side walls each havingupper and lower. edgesand an end, said ends being curved where they meetthe upper edges of the walls, and a continuous integral ductile sheetmetal seal channel following the curve and extending along the upperedges and ending adjacent to the lower edges at the ends of the walls,the seal channel being wider than the space between the walls and havinga substantial disposed between the walls, and cooperative means on theseal channel and the walls for effecting a snap-action connectiontherebetween.

3. In a slab joint structure, the combination of a plurality of jointforms each of which comprises spaced walls and has an end, the formsbeing disposed with an end of one form adjacent the end of the next formwhereby to extend the forms in substantial longitudinal align'- ment, aseal channel connecting the edges of the walls and extending into thespace between the walls whereby to provide a recess in the end` of eachform, and asplicing memberhaving opposed edges conforming in shape andsi'ze to the recesses in the ends of the forms and fitted within therecesses of the forms to provide a sealed connection between the ends ofthe forms. v

4. In a slab joint structure, the combination of a plurality of alignedjoint forms each of which comprises spaced walls and has an end and anupper edge, continuousintegral ductile sheet metal channel means alongthe upper edge and along the end of each form and extending into thespace between said walls whereby, to provide an outwardly openingrecess, a form splicing member having opposed edges fitted within theends of the forms, and a joint filler strip on the splicing memberextended beyond the opposed edges of the splicing member and into therecesses of the upper portion of the channel of each form.

5. A slab joint structure comprising in combination, a form comprisingperforated side walls spaced apartto provide a chamber, a load transferelement extended through the perforations of the side walls and havingan end thereof/projecting beyond. the plane of one of the side walls andhaving at its other end a substantial bearportion of said excessmaterial ing surface, and a' bearing member having a substantialbearingsurface and comprising a depending supporting leg and slidablysurrounding 'the projectingv end of the load transfer element,

vthe members having the substantial bearing sur' 5 y faces having endfaces abutting the side walls -'beyond which the bearing membersproject, to close the chamber to entry of grout in the region of. theflange, the load transfer element portion disposed between said sidewalls having suiilcient l0 strength for meeting the maximum shear loadthat may be imposed on said joint structure and the horizontal width ofsaid substantial bearing surfaces disposed at the ends o'f the loadytransfer element being much greater than the 15 width of said rstmentioned portion of said load transfer element.v 6. The combinationwith a pair of concrete slabs having adjacent ends .thereof spaced toprovide an expansion joint, of ,a plurality of load 'a transferJelements, each comprising a bar member of a `diameter suflicient tosustain itspropor-4 tional share of shear action at such joint, said barmembers being parallel with one another and with the surfaces of theslabs, said bar members extending throughl the space between the slabsand each having one end disposed within the body line of one slab andits other end disposed within the body line of the other slab, aplurality of bearing members' embedded in said slabs, a bear- 30 ingmember being provided for each end of each bar member, vthe bearingmembers associated with each bar being .adapted to accommodate the barmember toA relative expansion and contraction of the said members andslabs, and each bearing kmember having an enlarged transverse bearingsurtface adequate to transfer load from the con- I cre e to itsassociated bar member without destroying the bearing between theconcrete and the bearing -memben and reinforcement emo bedded in theconcrete and disposed 'adjacent the top face-of the concrete andthatsurface of the concrete at and along the expansion joint, thereinforcement at the top of the concrete ex' tending to a substantialdistance from the -expansion joint wherebyV to incorporate within the Kslabs, at thejoints thereof, the ability to with-` stand the tendencytoward bending or cantilever action of the? concerete slabs incident toth movement of aload from one slab, over the eX- pansion jointonto theadjacent slab.

7. A slab'joint structure comprising in combination, a form comprisingperforated side walls spaced apart to provide a chamber, the perforaitions in said side walls beingarranged in aligned pairs, a load transferpin extended through each pair of the perforations of the side walls andhaving'oppositeends, bearing means on said-opposite ends each comprisinga bearing sleeve having a substantial bearing surface to be embeddedin'the I slab, said sleeves each including an extending4 le`g reaching tothesubgrade so as to supportA the form in an upright position, andcooperative means on the form'and sleeves for preoluding rotation of thesleeves-` about the axes of the pins, the load transfer pin havingsuilicient strength for meeting maximum shearload to ,be directed l.against said'joint structure and the substantial bearing surfaces on thebearing means being of much greater width than the width of the transferpin. v l l 8. In combination, a slab joint form and means for supportingsaid form in an upright position upon a slab bed, a load transfer meansassociated with the form to connect slabs located at opposite sides ofthe form, and means for overcoming the destructive effects of cantilevertype forces directed upon one of the slabs, comprising an invertedchannel shaped reinforcing element having a pair of legs and anintermediate leg connecting portion, one of the legs being molded insaid one slab in close proximity to the form, and said intermediateconnecting portion being molded in the same slab close to the upper surface of the slab. v

, 9. A factory assembled slab joint structure comprising in combination,a form comprising upright metal Walls spaced to provide an expansionchamber, said walls being perforated transversely and including jointller supporting means along their upper edges, a load transfer meanscomprising ashear pin supported in the perforations and having oppositeends extending from-the side walls, a pair of pin bearing elements eachincluding a face abutting one of the form walls and a sleeve portionsurrounding an end of said shear pin, atleast one of said sleeves havinga frictionaly movable mounting upon its associated shear pin end ofsulcient security to hold the shear pin in position ag nst ordinarymanual handling incident to shipme t and placement ofthe joint form,said frictional relationship being inadequateto prevent relativemovement of the parts incident to changes in weather conditions. A

10. A factory assembled slab joint structure comprising in combination,a form comprising upright metal walls spaced to provide anV expansionchamber, said walls being perforated transversely and including jointfiller supporting means lalong their upper edges, 'a load transfer meanscomprising a shear` pin supported in the perforations and havingopposite ends extending from the side walls, a pair of pin bearingelements each including a face abutting one of the 1 form walls and a'sleeve portion surrounding an end of said shear pin, at least one ofsaid sleeves having a frictionally movable mounting upon its associatedshear pin end of sufficient security to hold the shear pin in positionagainst ordinary manual handling incident to shipment and placement ofthel joint'form, said frictional relationship being inadequate toprevent relative movement of the parts incident to changes in weatherconditions, and means including portions of the form walls, for closingthe bottom of the expansion chamber, the load transfer pin havingsufcient size and strength for meeting maximum shear load that may bedirected against said joint structure and the bearing elements being ofmuch greater width than the load transfer pin. i

1l. A factory assembled slab joint sturcture comprising in combination,a form comprising upright metal walls spaced to provide an expansionchamber, said walls being perforated transversely and including jointfiller supporting means along their upper edges, a load transfer meanscomprising a shear pin supported in the perforatons and having oppositeends extending from the side walls, a pair of pin bearing elements eachincluding a face abutting one of the form walls and a sleeve portionsurrounding an end of said shear pin, at least one of said sleeveshaving a frictionally movable mounting upon its associated shear pinendof sufficient security to hold the shear pin in'position againstordinary manual'handlingincdent to shipment and placement of the jointform,vsaid frictional relationship being inadequate to prevent relativemovemi 0f the Pans nels-19M l@ @langes in restes? conditions, meansincluding portions of the form walls, for closing the bottom of theexpansion pansion chamber. 5 n

12. A slab joint form comprising a pair of spaced side walls each havingupper and lower edges, and ends connecting the said upper and loweredges, the upper edges and ends being curved at their juncture, saidwalls being each of a generally rectangular formexcept for the curvedupper corners thereof, and a continuous integral seal channel of`c0ppperor other noncorresive sheet metal, following the form of said upper, endand curved edges of side walls, said seal channel having a dependingcentral portion extending into the space between said side walls andhaving flanges extending laterally beyond and resting upon the upper,end and curved kedges of the side walls.

13. A slab joint form comprising a pair of spaced side wals each havingupper and lower spaced side walls each having upper end lower edges andan end, said ends being curved where they meet the upper edges of thewalls, and a continuous integral seal, channel following the curve andextending alongvthe upper edges and l ending adjacentl to the loweredges at the ends of the walls, said seal channel comprising laterallyextending flanges projecting outwardly beyond the side walls.

l5. A slab joint form comprising a pair of .spaced side walls eachhaving upper and lower edges and an end, said ends being curved wherethey meet the upper edges of the walls, and a continuous integral sealchannel following the curve and extending along the upper edges and endadjacent to the lower edges at the ends of the walls, said seal channelcomprising laterally extending flanges projecting outwardly beyond theside walls, said seal channel also comprising a central corrugatedportion extending longitudinally of the Aseal channel and projectinginto the space between the sidewalls.

16. The combination with a pair of concerete slabs having adjacent endsthereof spaced to Provide an'expansion joint, of a plurality of loadtransfer elements each comprising a bar member of a diameter suicient tosustain its proportional share of shear action at such joint, said barmembers being parallel with one another and with the surfaces of theslabs, said bar members extending through the space between the slabsland each having one end disposed within the body line of one'slab andits other end disposed within the body line of the other slab, aplurality of bearing members embedded in said slabs, a bearing memberbeing provided for each end of each bar member, the bearing membersassociated with each bar being adapted to accommodate the bar member torelative expansion and-contraction of the said members and slabs, andeach bearing member Vhaving an enlarged transverse bearing suI aceadequate to transfer lPQ- .flom the concrete tants associated bar memberwithout destroying `the bearing between the concrete and the bearingmember, and reinforcement embedded in the concrete and disposed adjacentthe top face of the concrete, the reinforcement at the top of theconcrete extending a substantial distance from the expansion jointwhereby to withstand the tendency toward bending or cantilever action ofthe concrete slabs incident to the movement of a load from one slab,over the expansion joint onto the adjacent slab.

17. In combination, a slab joint form and means for supporting said formin an upright position upon a slab bed, a load transfer means'associated with the form to connect slabs located at opposite sides ofthe form, and means for overcoming the destructiveeffects of cantilevertype forces directed upon one of the slabs, comprising a reinforcingelement having a leg molded in one slab in close proximity to the formand having a portion extending a substantial distance longitudinally ofthe slab and 4being molded in glei) same slab close to the upper surfaceof the 18. The combination with a pair of concrete slabs, of a combinedslab spacing and joint providing means comprising a slab joint form,means disposed at the inside of the curve, which method for supportingsaid form in an upright position upon a bed for the slabs and betweenthe pair 'of concrete slabs,a load transfer means associated with theform to connect the pair of concrete slabs, said transfer meanscomprising dowel pins extending through the form and being oi' across-section adequate to withstand the approximate maximum shear forcesto be directed upon theslabs incident to movement of ltractionallysupported loads-from one of said slabs to theother of said slabs andbearing sleeves within the body lines o'f the concrete slabs and each ofsaid sleeves receiving an end of one of the' dowel pins, the dowel pinsbeing adapted to move longitudinally relative to the sleeves, thebearing sleeves being of overall transverse proportions substantiallylarger than the cross-sectional dimension of the dowel pins whereby tohave an effective bearing vsurface of adequate size to distribute theshear load di- .rected upon the dowel pins, to the concrete withoutcrushing the bond betweenthe sleeves and the concrete slabs, and meansfor overcoming the destructive effect of cantilever type forces directedupon one of the slabs and comprising a reinforcing element embedded linsuch concrete slab, close to the surface of the slab and,

extending a substantial distance from said Jointl form longitudinally ofthe slab.

19. The combination with a pair of concrete slabs, of a'combined slabspacing and joint providing means comprising a slab joint form, meansfor supporting said form in an upright position upon a bed for the slabsand between the pair of concrete slabs, a load transfer means associatedwith the form to connect the pair of concrete slabs, said transfer meanscomprising dowel `pins extending through the form and being of across-section adequate to withstand the approximate maximum shear forcesto be directed upon y the slabs incident. to movement of tractionallysupported loads from one of said slabs to the other of said slabs andbearing sleeves within the pins, to the concrete without lcrushing thebond `l0 between the sleeves and the concrete slabs, means forovercoming the destructive eifect'of cantilever type forces directedupon one of the slabs and comprising a reinforcing element embedded insuch concrete slab, close to the surface of the l5 slab and extending asubstantial distance from said joint form longitudinally ofthe slab, andan expansible element resistant seal extending transversely of the forniand having its opposite lateral edges anchored in the concrete slabs.

20. The method of forming a at elongated strip of ductile metal into acontinuous strip having sections at right angle to one another, each ofU-shape cross section and connected by an in-` termediatecurvedfsection. of similar cross see- 2,5

tion and having the base of the U-shape portion comprises the steps ofbending a s'trip of ductile metal into channel formation, and curvingthe channel while stretching it lengthwise to prehaving sections atrightangle to one another, 35

each of U-shape cross section and connected by an intermediate curvedsection of similar cross section and havingthe base of the U-shapeportion disposed at the inside of the curve, which method comprises thesteps of treating a flat strip 40 of soft non-rusting metal to form astraight channel intermediate its ends, leaving the ends of the strip ina substantially flat condition, and thereafter treating said ends tobend them into Acurved channel formation while at the same timestretching said ends sufliciently yto preclude crinkling and avoiddensification of/the metal at the curved portions thereof, the channelsat the curved portions meeting the channel of the in- -terme'diateportion. 50 22. A`slab joint form comprising a pair of.,

spaced vertical side wallsreach having upper, lower and end `edges,saidedges being substanstially aligned at every place transversely ofsaid pair of walls, said wall edges being curved at the upper cornersthereof, and an elongated continuous integral ductile sheet metal sealcoextensive with the topand end edges of the side walls and having itslongitudinal central portion of generally U-shaped cross section atevery o point longitudinally thereofV and comprising lat-l, erallyextending iianges extending from said cen-` tral portion thereof, thesaid U-shaped portion being disposed between the side walls and thelaterally extending flanges being supported by the adjacent edges of theside walls and extended beyond said side walls for embedment in aplastic mass disposed on opposite sides of said form.

v SAMUEL KLEIN.

CERTIFICATE OF CORRECTION. Paterit No. 2,181,625. November 2g, 1959.

SAMUEL KLEIN.

It is hereby certified that error appears in the printed specificationOT the above numbered. patent requiring correction as follows: Page9,f1rst column, lino 25, claim 9, for "frictionaly" read frictionally;and second column, line 15-111, claimlZ, fox` non-corrosive readnon-Gorros ive; line 22, claim 15, for "wals" read walls; line 35, claimlh, for "end read and; and-that the said Letters Patent, should beroadwith this correction therein that the seme may conform to the recordof the case in the Patent Office.

Signed. and sealed this 15th day of February, A. D. 19110.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

